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Mt Hood

Issued: 6:04 PM PST Thursday, February 1, 2018
by Dallas Glass

NWAC avalanche forecasts apply to backcountry avalanche terrain in the Olympics, Washington Cascades and Mt Hood area. These forecasts do not apply to developed ski areas, avalanche terrain affecting highways and higher terrain on the volcanic peaks above the Cascade crest level. 

Precipitation type will determine avalanche conditions Friday. In areas receiving snow, identify and avoid steep wind loaded slopes below cornices, with wind drifts, or near uneven snow surfaces. In locations receiving rain, avoid avalanche terrain where being caught in even a small Loose Wet avalanches could have dire consequences such as above cliffs, open creeks, or gullies.

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Avalanche Problems for Friday

Wind Slabi

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.

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Loose Weti

Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.

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Forecast for Friday:

Warm wet weather will continue to drive avalanche conditions on Friday. Avalanche hazard will be largely dependent on precipitation type and intensities.

In locations receiving snow, strong winds will continue to build new Wind Slabs on lee slopes. You will be able to trigger these avalanches in steep terrain where winds are depositing snow. Avoid steep slopes below cornices, with wind drifts, or near uneven snow surfaces.

Very large avalanches have occurred above treeline in the past week. While these avalanches may be nearly impossible for a backcountry traveler to trigger, there is a high degree of uncertainty around these slab releases. Caution should be taken if traveling above treeline or through the tracks and runouts of avalanche paths originating above treeline.

In areas receiving rain, wet surface snow will lead to Loose Wet avalanche conditions. Watch for new roller balls and pinwheels as these are signs that you are more likely to trigger an avalanche. Avoid steep slopes with wet surface snow. Extra caution should be taken in terrain where even small avalanches could have dangerous consequences.

Avalanche Summary:

As of Thursday afternoon, 4-8 inches of settled snow sits above the 1/29 crust layers. Observations indicate the recent snow is well bonded to the old crust.

A long and stormy last two weeks of January built deep Wind Slabs near and above treeline. During a break in the weather, explosives were able to trigger multiple very large avalanches. The avalanches entrained significant snow becoming very large and destructive. Reports indicate some of these avalanches destroyed mature trees.

Observations

On Thursday, NWAC pro-observer Laura Green traveled in Newton and Heather Canyons. She found light rain beginning to wet the snow surface by mid-afternoon. Winds were increasing throughout the day.

On Wednesday, Mt Hood Meadows Pro Patrol reported the surface snow was sculpted by recent winds creating variable snow surfaces and scoured ridgelines. Below treeline, 6-8" of snow was well bonded to the 1/29 semi-supportable crust. 

Mt Hood Meadows Pro Patrol Sunday reported multiple very large artillery-released avalanches with crowns up to 12 ft range, running on steep NE and ENE terrain above treeline and travelling very long distances, in one case snapping 20+ year old trees.

No Corresponding Mountain Weather Forecast Available

USE AT YOUR OWN RISK

This Backcountry Avalanche Forecast is provided in conjunction with the US Forest Service, and is intended for personal and recreational purposes only. Safe backcountry travel requires preparation and planning, and this information may be used for planning purposes but does not provide all the information necessary for backcountry travel. Advanced avalanche education is strongly encouraged.

The user acknowledges that it is impossible to accurately predict natural events such as avalanches in every instance, and the accuracy or reliability of the data provided here is not guaranteed in any way. This forecast describes general avalanche conditions and local variations will always occur. This forecast expires 24 hours after the posted time unless noted otherwise.